Hi, David. On Thu, 2010-02-11 at 01:14 -0800, David Rientjes wrote: > > > +/* > > > + * Tasks that fork a very large number of children with seperate address > > > spaces > > > + * may be the result of a bug, user error, or a malicious application. The > > > oom > > > + * killer assesses a penalty equaling > > > > It could also be the result of the system getting many client > > connections - think of overloaded mail, web or database servers. > > > > True, that's a great example of why child tasks should be sacrificed for > the parent: if the oom killer is being called then we are truly overloaded > and there's no shame in killing excessive client connections to recover, > otherwise we might find the entire server becoming unresponsive. The user > can easily tune to /proc/sys/vm/oom_forkbomb_thres to define what > "excessive" is to assess the penalty, if any. I'll add that to the > comment if we require a second revision. > I am worried about opposite case. If forkbomb parent makes so many children in a short time(ex, 2000 per second) continuously and we kill a child continuously not parent, system is almost unresponsible, I think. I suffered from that case in LTP and no swap system. It might be a corner case but might happen in real. I think we could have two types of forkbomb. Normal forkbomb : apache, DB server and so on. Buggy forkbomb: It's mistake of user. We can control normal forkbomb by oom_forkbomb_thres. But how about handling buggy forkbomb? If we make sure this task is buggy forkbomb, it would be better to kill it. But it's hard to make sure it's a buggy forkbomb. Could we solve this problem by following as? If OOM selects victim and then the one was selected victim right before and it's repeatable 5 times for example, then we kill the victim(buggy forkbom) itself not child of one. It is assumed normal forkbomb is controlled by admin who uses oom_forkbomb_thres well. So it doesn't happen selecting victim continuously above five time. -- Kind regards, Minchan Kim -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>